RC-4

internal/runtime/state.go

@@ -176,6 +176,57 @@ type AcceptResult struct {
 	Improved bool
 }
 
+// CanSubmit validates sequence and per-client timing before a request is
+// admitted into the global-per-task lottery. It does not mutate state, so an
+// unselected ticket can be consumed explicitly by SkipLottery.
+func (s *State) CanSubmit(task data.Task, cid string, seq int64, minInterval time.Duration) error {
+	k := guessKey{task.ID, cid}
+	now := time.Now().UTC()
+	s.mu.RLock()
+	g, ok := s.guesses[k]
+	s.mu.RUnlock()
+	if !ok || g.PublicSeed != task.PublicSeed || seq != g.NextSeq {
+		s.record(false, false, true)
+		return ErrBadSequence
+	}
+	if !g.LastGuess.IsZero() && minInterval > 0 && now.Sub(g.LastGuess) < minInterval {
+		s.record(false, false, true)
+		return ErrRateLimited
+	}
+	return nil
+}
+
+// SkipLottery consumes a valid sequence that lost the random draw without
+// evaluating/scoring it. This prevents the same deterministic guess from being
+// resubmitted forever while keeping guess_count reserved for actually accepted
+// and evaluated tips.
+func (s *State) SkipLottery(task data.Task, cid string, seq int64, minInterval time.Duration) (int64, error) {
+	k := guessKey{task.ID, cid}
+	now := time.Now().UTC()
+	s.mu.Lock()
+	g, ok := s.guesses[k]
+	if !ok || g.PublicSeed != task.PublicSeed || seq != g.NextSeq {
+		next := g.NextSeq
+		s.mu.Unlock()
+		s.record(false, false, true)
+		return next, ErrBadSequence
+	}
+	if !g.LastGuess.IsZero() && minInterval > 0 && now.Sub(g.LastGuess) < minInterval {
+		next := g.NextSeq
+		s.mu.Unlock()
+		s.record(false, false, true)
+		return next, ErrRateLimited
+	}
+	g.NextSeq++
+	g.LastGuess = now
+	g.Revision = task.Revision
+	s.guesses[k] = g
+	next := g.NextSeq
+	s.mu.Unlock()
+	s.record(false, false, true)
+	return next, nil
+}
+
 func (s *State) Accept(task data.Task, cid string, seq int64, score float64, minInterval time.Duration) (AcceptResult, error) {
 	k := guessKey{task.ID, cid}
 	now := time.Now().UTC()

internal/runtime/state_test.go

@@ -79,3 +79,26 @@ func TestGuessHotPathAndReroll(t *testing.T) {
 		t.Fatalf("reroll not reset: %+v", g)
 	}
 }
+
+func TestLotterySkipConsumesSequenceWithoutCountingAcceptedGuess(t *testing.T) {
+	s := New()
+	task := data.Task{ID: "lottery-task", PublicSeed: "seed", Revision: 1}
+	s.InitGuess(task, "client", GuessState{})
+	if err := s.CanSubmit(task, "client", 0, 0); err != nil {
+		t.Fatalf("eligible guess rejected: %v", err)
+	}
+	next, err := s.SkipLottery(task, "client", 0, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if next != 1 {
+		t.Fatalf("next seq = %d, want 1", next)
+	}
+	g, ok := s.Current(task, "client")
+	if !ok {
+		t.Fatal("missing runtime state")
+	}
+	if g.NextSeq != 1 || g.GuessCount != 0 || g.LastGuess.IsZero() {
+		t.Fatalf("unexpected lottery skip state: %+v", g)
+	}
+}